Compound air-compressor



(No Model.)

B. HILL.

COMPOUND AIR COMPRESSOR.

Patented July 25, 1882.

WITNESSES UNITED STATES PATENT OFFICE.

EBENEZER HILL, OF SOUTH NORWALK, CONNECTICUT.

COMPOUND AlR-COMPRESSO R.

SPECIFICATION forming part of Letters Patent No. 261,606, dated July 25,1882.

Application filed December 16, 1880. (No model.)

To all whom it may concern:

Be it known that I, EBENEZER. HILL, of South N orwalk, in the county ofFairfield and State of Connecticut, have invented new and usefulImprovements in Compound Air-Compressors, of which the following is aspecificaion. This invention pertains to certain improvements incompound air-compressors in which two or more compressing-cylinders areused and are driven by a steam-engine.

The invention consists, first, in combining two ormore air or gascompression pumps with a steam-engine and a fly-wheel shaft in such amanner that the piston-rod of the steam-engine will be in line with thepiston-rods of the compression-pumps and either below or above thefly-wheel shaft, and said shaft will be in line with the center of thecross-head wrists that drive the said fly-wheel shaft, as willhereinafter appear.

Second. This invention also consists in combining with anair-compressing engine having two or more compressing pumps or cylindersa slide-valve or its equivalent, as an inlet-valve to the first cylinderand operated by positive mechanism from the main shaft of the engine, aswill hereinafter appear.

Third. Theinvention also consistsin combining a cooling orwater-circulating apparatus with two or more compression cylinders orpumps in-such a manner that the water or cooling agent begins tocirculate around thefirst compression-cylinder, and thence throughconduits leading to the second cylinder, and thence around the secondcylinder or pump, and so on from the prior to the secondary pump in theentire system, as will hereinafter appear.

In the drawings, Figure 1 is a partial section and elevation of an airor gas compression engine having two compression-cylinders and asteam-engine with piston-rods in line with each other and a circulatingapparatus for a cooling agent between the compression-cylinders. Fig. 2is a section of the slides with the cross-head in elevation. Fig. 3 is aplan of the cross-head as seen from above it. Fig. 4 is a diagram toillustrate the relative positions of the cross-head with the crank andmain shaft.

At A is represented the bed or frame of the machine, upon which ismounted the steamengine, as at B, and two compressor-pumps, as at C andD, the one at C being the first or inlet-pump for the first compression.

The fly-wheel shaft is at E located between the steam-engine and one ofthe compressors, so that the entire mechanism may be combined in a smalland compact form upon the same bed or frame. The cylinders of the engineand the compressors are all so located that their piston-rods are inline, as represented at F F F and in this case are located below theflywheel shaft, but may be above, if desired. The piston-rod of thesecond compressor is in fact an extension of the rod of the engine, as

shown at Fig. 1, and extends through the'cylinder and connects to ahorn,as at G, or adepending projection from the cross-head,which isshown at H, and which is mounted on slides, as at K, in such a positionthat its wrists are in the same plane with the fiy-wh'eel shaft, andtherefore the crank-pins, as at L, on the flywheels will have equalvelocities in equal spaces in any portion of their revolution, or asillustrated in the diagram at Fig. 4., where E is the main shaft, and Lthe crank-pin, and G the cross-head. Now, when the crank is turned up,as shown in full lines, acertain angle is made at L, and when the crankis turned down to the opposite point, as shown in dotted lines, the sameis produced, and so throughout the entire range of motion, the resultbeing to make the forward and back stroke of the piston in the sametime. In such an arrangement of the parts the power of this ongine isdirect acting to the pumps, instead of through cranks, as usually done,and the crosshead is only required to regulate the speed byfirstimparting motion totheflywheel or wheels, as the case may be, andin turn from them to the piston-rods. Said horn G, which connects thepiston-rods to the cross-head, is made coneshaped, as at G, and titsinto a corresponding box, as at G which is fitted into the crosshead,and is held in position by a cap and screw-bolt, as at G and C", so thatsaid horn may be rotated in said box, if desired.

Upon the lower end of the horn G is a horizontal sleeve, as at G thatreceives the ends of the piston-rods F and F with conical ends,

as shown, and that are fastened in thesleeve by keys in the ordinarymanner. By such an arrangement itis evident that if from any cause theconnecting-rods on one side should be a little longer or shorter than onthe other there would be no cramping of the parts, as the cross-headcould vibrate on the conical-shaped horn at G, and it also serves as aneasy means of adjustment. I

Goncernin g the second part of my invention, which pertains to the useof a slide-valve in combination with compound air-compressors, it may behere remarked that theinlet-valve here shown at M is of the form knownas the gridiron slide-valve, and it is operated by an cecentric, as atM, on the main shaft, through a lever, M and a connecting-rod,M whichengages with the valve by lugs which extend through the cover of thevalve-chest, and thereby causes regular reciprocations, according to therevolution of the main shaft; but I do not wish to limit myself toslide-valves and eccentrics, but wish to use any of thepositively-operated valves common to engines and pumps. The qualities,however, desired in a slide air inlet valve arelargeport-area and aproper time for opening; but in making a large port-area a largeclearance-space is unavoidable. and said space is objectionable from thefact that air at each stroke of the piston is compressed, but notdischarged, and hence a loss of efliciency in the machine; but if theinlet-valve be kept closed for a time after the piston recedes on itsreturn stroke, then the air which has been left behind in a compressedstate will expand until it reaches atmospheric pressure, and while soexpanding will return its pressure upon the piston. When the air soexpanded has reached atmospheric pressure, then is the proper time foropening the inlet-valve; but if opened before, then some pressure wouldbe lost, and if not till afterward, then a partial vacuum is formedbehind the piston. Now, if it were possible to preserve a constantpressure against which the piston is working, then avalve could beeasily constructed and set to work properly under such conditions; butif there is any changein saidpressures-as,forexample,where a singlecylinder is working into a reservoir from which varying pressures arerequiredthen it is evident a corresponding change must be made in thetime of opening the inletvalve; but suchacapacity oradaptation of theparts would require very complicated mechanism, and therefore todetermine the exact time at which said valve maybe opened and closed asecond compression-pump is employed, of smaller diameter than the first,and into which the air from the inlet-cylinder is forced. This secondcylinder encounters the varying pressures in the air-reservoir, and isprovided with the ordinary automatic puppet-valves, and

hence the first pump only forces into the secend and smaller pump, andthe pressure in the first never rises beyond aknown point predeterminedby the relative proportions of the two cylinders, and which is of coursedetermined when the engines are constructed, and which could not be thecase if a second cylinder were not used. Again, the pressure in theinlet pump or cylinder is much less than the pressure of the reservoir,and hence the friction of the slide-valve is much lighter than it wouldhe were the large cylinder to discharge directly into the reservoir, orwithout any compound cylinders or pumps, and therefore by such acombination all the heretofore-troublesome objections to the use ofslide-valves in air-compressors are overcome without loss of power orcostly attachments, and all the advantages of the serial and compoundingpressures are at the same time secured.

The third part of the invention relates to the cooling devices,in whichthin linings are used for the compression pumps, as already described ina previous application for a. patent, one of said linings being shown atN in the large or inlet compressor at G, and which forms awater-chamber, as at 0, into which water is admitted through a pipe, asat P, and

after circulating around said thin liniugin the first cylinder passesout through a pipe, as at R, to a cooling apparatus, as at S, which isintermediate between the compressors G and I). This cooling apparatusmay be of any desired form, but, as here shown,is cylindrical, andcontains thin tubes, as at T, through which the air from the first pumppasses to the second, and the water circulates around them in the outercase, S.

Defiecting-plates, as at W, may also be introduced to more thoroughlycirculate the water from side to side in the outer casing, and then thewater is conducted by pipe R to the water-chamber in the secondcylinder, where a thin lining is used, as in the first, and around thisthe water circulates and finally passes off through an outlet-pipe, asat X. As already described, the water begins its circulation in thefirst cylinder, and thence on through the cooling apparatus, and thenthrough the second. This direction of the passage of the water is veryimportant, as the coldest water comes in contact with the inlet-aircylinder, where the first part of the total compression is effected, andit is known to engineers that the increment of heat from compression isgreatest during its early stages, and hence it is desirable to have thecooling process most efficient at that time. As the air duringcompression passes through the machine the water follows, and by reasonof the successive compressions the temperature of the air is continuallyabove that of the water, and the water continues to receive heat untilfinally discharged, and thus a given amount of water becomes hotter andcarries away more heat by circulating in the direction of thecompression than in any other way.

It is evident that in carrying out this part of my invention thecylinders may be arranged in a difl'erent position from that shown, and

that the air-cylinders may be attached to different engines; also, thatmore than two compressors may be used, if desired.

I'therefore claim 1. The combination, with the-cross-head, of the horn Gand its sleeve for connecting the piston-rods of air-compressin g pumps,as hereinbefore set forth.

2. The combination of a positive-movement air-inlet valve with compound.cylinders in which serial compression is produced, whereby the workingpressure of the inlet-cylinder is rendered practically uniform by theproportionate sizes of the several cylinders, as hereinbefore set forth.

3. In compound air-compressors, the combination of water-spaces in thecylinders and intermediate cooling apparatus with suitable inlet andoutlet pipes, whereby the water will be caused to circulate in thedirection of the 20 air during the operation of compression, ashereinbefore set forth.

' In testimony whereof I have hereunto set my hand and seal in thepresence of two subscribing witnesses.

EBENEZER HILL. [L- s.]

Witnesses EUGENE N. ELIOT, CHAS. BARTRAM.

